The present invention relates to diagnostic devices, and more particularly to a device for diagnosing a liquid sample.
It is frequently desirable to determine the presence of bacteria in body fluids of a patient, such as blood or urine, for purposes of diagnosis. For example, a major problem confronting hospitals today is the determination of urinary tract infections. Although chills, fever, dysuria and frequency of urination may indicate infection, the incidence of asymptomatic urinary tract infection has been shown to be a common occurence. This asymptomatic infection is clinically diagnosed by testing for bacteria, which literally means the presence of bacteria in the urine. Clean voided urine from normal individuals generally contains microorganisms, which are indigenous residents of the urethra. Urine in the bladder, on the other hand, is ordinarily sterile, and the presence of any bacteria in the upper urinary tract is considered abnormal. Significant bacteriuria is a term that has been used to describe the numbers of bacteria in voided urine that exceed the numbers usually due to contamination from the anterior urethra and are in the range of the bacterial titers usually found in infected bladder urine. It has been established that a guideline for determination of bladder bacteriuria is the presence of 100,000 or more bacteria per milliliter in whole voided urine, although 70 to 85% of most cases of bacteriuria are characterized by counts of over 1,000,000 organisms per milliliter.
Since the presence of bacteriuria may be determined by the number of organisms in the urine, it has been found advantageous to use culture media for determining the number of bacteria in a sample of the urine. Presently hospitals and laboratories frequently collect a sample of body fluid, such as urine or blood, in a receptacle, and transfer the collected fluid from the receptacle to a culture bottle. However, the time lag encountered with this type of procedure presents a recurrent problem, and may cause unreliability in the test results. For example, urine presents an ideal growth medium for microorganisms, and certain species of bacteria may double in number in as little as 20 minutes. Accordingly, the assessment of urine for bacteriuria should be made immediately after the specimen is voided, since a sufficient time lag makes a distinction between significant infection and an overgrowth of contaminants impossible. Likewise, other microorganisms are so sensitive to their environment that they are unable to survive the delay, and the inoculation media will not present a true picture for the diagnostician. Thus, it is desirable to reduce the delay between taking the sample of the body fluid and the subsequent inoculation of culture medium with the sample, as well as preventing contamination of the sample.